Lock stitch sewing machine



y 4, 1937. N. v. CHRISTENSEN 2,079,568

LOCK STITCH SEWING MACHINE Filed Dec. 20, 1934 2 Sheets-Sheet l H H I S.

k WWI mwmlfihm g g H l \\\\J I f i k l I j J v I J WITNESSES N INVENTOR:

*1 mrmmyhrismnszzm May 4, 1937. v, HR|$TEN5EN 2,079,568

LOCK STITCH SEWING MACHINE Filed Dec. 20, 1934 2 Sheets-Sheet 2 FIGE;

.,I QWAW'VVH n Y WITNBSSES: Z 17 INVENTOR:

normanv'nrbstenszan if 22 V Patented May 4, .1937

' UNITED. STATES PATENT orr ce 8 Claims. (Cl. 112-256)- This invention relates to lock stitch sewins machines; and it is concerned more particularly with means for continuously cooling and at the same time continuously lubricating the rapidly revolving rotary hooks of such machines.

Recently, lock stitch sewing machines have been,

extensively improved structurally with the result of reducing vibration and increasing the speed of operation. At high speeds considerable heat is generated by friction between the relatively moving surfaces of the rotary hook and its associated bobbin case holder with attendant rapid wear due in part to inadequate lubrication of these elements. The present inventionisdirected toward obviating the above mentioned drawbacks, which I accomplish through provision of a simple means whereby a current of cooling air carrying a minute quantity of oil is continuously discharged upon the rotatinghook, the lubricant entrained in the air being restricted in amount to assure effective lubrication without the possibility of flooding the parts or appreciably aflecting the thread.

I speak of. the current of air as continuous, notwithstanding that it is produced by a reciprocatingpump, for the reciprocation is so very rapid that the continuity of the current is substantially unbroken. I 0 To properly accomplish the purposes of my invention, I cause this continuous supply of air to carry a constant minimum of oil. This oil is not atomized for this would entail the supply of too much oil. Instead evaporation is relied upon 5 to provide a constant minimum of oil. To lubricate the raceway between the rotary hook and the bobbin holder, a minute quantity of this evaporated oil is continuously deposited on the surface of the bobbin holder and related parts over which the thread slips. The passage of the thread loop helps to lead the deposited oil to the raceway where it is needed. In any oiling system in which the thread plays a part, the quantity of oil supplied must be reduced to a minimum in order to avoid disfiguring-the seam. The stream of air which carries this minute quantity of oil is efllcient to accomplish not only the oiling function thus described but also to keep the surface of the rotary hook and its related partsfree from the blanket of lint which tends to surround it and also to cool its temperature down to thatof the surrounding atmosphere.

A further object of my invention is to provide a combined rotary hook cooling and lubricating means in which both of these functions are continuously performed at a small expense of power for actuation or'of care from the attendant." Still other objects and attendant advantages will be clear from the following description and 60 the drawings.

In the drawings:

Fig. I is a fragmentary plan view of the base portion of a rotary hook. sewing machine fitted with my improved hook cooling and lubricating means, portions of the machine being broken away and sectioned to expose details of the invention.

Fig. II is a detail section drawn to a larger scale and taken as indicated by the arrows 11-11 in Fig. I.

Fig. III is a fragmentary cross sectional view taken as indicated by the arrows III-III in Fig. I and likewise drawn to a larger scale.

. Fig. IV is a detail plan section taken as indicated by the arrows IV-IV in Fig. II, likewise drawn to a' largerscale.

Fig. V is a perspective view of the reservoir for the oil used in the lubrication of the rotary hook.

In the illustrated sewing machine, the rotary hook i which is centrally-open at the back, and which revolves about the stationary bobbin case holder 2. is secured to a counter-shaft 3 journaled in a bearing 4 underneath the bed plate 5 of'the machine, said shaft being driven at increased speed from. the main shaft 6 of the machine through a pair of intermeshing spur gears I. The bearing 4 projects from a casing 8 which houses the gears I and which is filled with oil or grease to continuously lubricate them.

The combined hook cooling and lubricating means constituting the present invention, comprises an air pump it whereof the cylinder Ii is secured, by means of screws i2, to .the underside of the bed plate 5 of the machine. Reciprocating within the cylinder II is a piston i3 which is actuated by an eccentric N from the main shaft 8. The pump it is lubricatedthro'ugh an oil hole l5 accessible from the top of the bed plate 5, and its piston 13 is provided with a circumferential groove i8 to facilitate distribution of the oil within the cylinder ii. The performance of the pump i0 is controlled by a double acting check valve concealed within the head ll of the cylinder ii, said check valve comprising spring influenced closure balls l8 and i9 that cooperate with inlet and outlet ports 20 and II within the cylinder head ll. During the suction strokes of the piston i3, atmospheric air is drawn in through the port 20 past the closure ball l8 into the pump cylinder ii and during the pressure strokes of the piston, the charges of airthus drawn in are expelled from the cylinder past the closure ball i9 into a nozzle 22 which is connected to the valve head I l by means of a convenient form of coupling nipple 23. As shown in Figs. I and II the discharge end of the nozzle 22 is flattened as at 22a to provide a narrow flaring mouth. and bent so that the discharged air current is directed toward the rotary hook i at an angle so that part of it enters the centrally-open back of the hook and impinges upon the interior surfaces, while the remainder impinges upon and passes over the external surfaces.

From Figs. I, II and IV, it will be noted that the air inlet 20 of the pump communicates with an open-top well 25 which is integrally formed with the pump cylinder H and into which projects the down-turned end 26a of a tube 16 leading horizontally from an oil reservoir 21 secured to the bottom face of the bed plate 5 by screws 28. Coiled within the reservoir 21 is a wick 29 whereof one end is threaded through the tube 26 with a portion 29a thereof projecting beyond the downwardly bent end 26a of said tube (see Fig. II)

within the well 25 of the pump cylinder I I so as to be exposed to the inflowing air. The reservoir 21 is kept filled with oil so that thewick 29 is completely saturated at all times, the oil being introduced into said reservoir through a hole at in the bed plate of the machine. By the joint action of gravity and capillarity, the end 29a of the wick 29 is kept moist with oil so that within the region of the downward end of the tube 26. a minute quantity of oil is constantly vaporized and intimately absorbed by the air as it is drawn into the inlet port of the pump. The current of air carries its oil tothe rotary hook and its related parts and deposits itupon these parts, and from thence with the aid oftheslippage of thread around the bobbin case the oil is led to the surfaces of the raceway and lubricates them. the supply of oil being at all times so minute as to avoid any objectionable effect by reason of the absorption of any of it by the thread. The end of the wick is in contact not with an air blast but with a gently moving column of air en'tering all around it and facilitating evaporation without atomization. The arrangement of oil reservoir and wick insures continuity of supply of oil at a constant but minimum rateand not intermittent lubrication. The proportion of the oil carried by the air is very minute and is regulated by adjusting the projection of the wick 29 beyond the end 26a of the tube 25 within the well. While this lubrication process is proceeding, the same current of air effectively cleans and cools the parts with which it comes in. contact both interiorly and exteriorly and prevents heating and lessens wear.

Having thus described my invention, Iclalm:

1. In a lock stitch sewing machine, a centrallyopen rotary hook and a stationary bobbin case holder frictionally engaged by the rotary hock, means for cooling the rotary hook and keeping it I clean of lint and dirt, including a reciprocating air pump with an air inlet and an air outlet, and a nozzle connected to the pump outlet whereby the air compressed by the pump is directed partly into the interior and partly onto the exterior of the hook; and lubricant dispensing means associated with the pump whereby a suflicient quan tity of oil is carried along with the air entering the pump inlet to lubricate the lnterengaged parts of the bobbin case holder and the rotary hook. 5 I 2. In a lock stitch sewing machine having a centrally-open rotary hook and a stationary bobbin case holder frictionally engaged by the hook, means for cooling the rotary hook and keeping it clean of lint and dirt, including a reciprocating 7 air pump with an air inlet and an air outlet, and a nozzle connected to the pump outlet whereby air compressed by the pump is directed at an angle toward the hook, so that part of it enters the interior of said heck through the open back and part thereof flows about the exterior of the hook; and lubricant dispensing means associated with the pump whereby a suflicient quantity of oil is carried along with the air entering the pump inlet to lubricate the interengaged parts of the bobbin case holder and the rotary hook.

3. In a lock stitch sewing machine, a. main shaft; a counter shaft with' a centrally-open rotary hook thereon, driven at increased speed from the main shaft; a stationary bobbin case holder frictionally engaged by the hook; means for cooling the rotary hook and keeping it clean of the bobbin case holder and the rotary hook.

4. In a lock stitch sewing machine having a centrally-open rotary hook and a stationary bobb n case holder frictionally engaged by the hook;

' means for cooling the rotary hook and keeping it clean of lint and dirt, including a reciprocating air pump with an air inlet and an air outlet, and a nozzle connected to the pump outlet whereby the air compressed by the pump is directed partly into the interior and partly onto the exterior of'the hook; an oil'reservoir exteriorly of the pump; and a wick extending from the reservoir to a point adjacent the air inlet of the pump so that a definite quantity of oil is carried along with the air to lubricate the-interengaged parts of the bobbin case holder and the hook.

5. In a lock stitch sewing machine having a centrally-open rotary hook and a stationary bobbin case holder frictionally engaged by the hook, means for cooling the rotary hook and keeping it clean of lint and dirt, including a reciprocating air pump with an air inlet and an air outlet, and a nozzle connected to the pump outlet whereby the air compressed by the pump is directed partly into the interior and partly onto the exterior of the hook; an oil reservoir exteriorly of the pump; and a wick extending from the reservoir and terminating within a suction well adjacent the air inlet of the pump so that an amount of oil dependent upon the exposure of the wick at its terminus within said well is drawn into the pump by the air for lubrication of the'interengaging parts of the bobbin case holder and the hook.

6. In a lock stitch sewing machine a rotary book, a stationary bobbin case holder with parts frictionally engaging the rotary'hook, means for creating a current of air and discharging the same upon the rotary hook whereby it is cooled, and an oil dispensing instrumentality so disposed exteriorly of the pump in the course of said current of air that small particles of oil are carried by the air in suflicient quantity to lubricate the interengaging parts of the bobbin cas'e holder and the rotary hook.

NORMAN V. CHRISTENSEN. 

